Display part runs Android
The Transformer Book Trio display part sports an 11.6" 1080p panel, and is powered by a lowly Intel Atom Z2760 1.6 GHz dual-core processor plus 2 GB of RAM. It will come in 16, 32, or 64 GB capacities. That tablet side of things is running Android 4.2.2, and you can't use it as a Windows slate. It, however, is 304.9 x 193.8 x 9.7mm, and weighs 700g, so lugging it around won't be fun.
Dock part runs Windows 8
The "PC Station" dock weighs even more at 1kg, and with its 304.9 x 193.8 x 13.4mm dimensions the whole setup is a bit bulkier than some compact ultrabooks. When attached to the keyboard dock, however, you can use the full Windows 8, powered by your choice of processor up to an Intel Core i7 Haswell chip, 4GB of RAM, and up to 1 TB of storage. ASUS says you'll get up to 13 hours of battery running Android (with the keyboard dock), but just 5 hours running Windows 8, despite the Haswell inside.
On the other hand, the keyboard dock itself can be hooked up to an external display, and used independently, and we found it to be light, of excellent build quality, and with decent key travel. Price and the time this ASUS Transformer Book Trio device will hit the shelves are yet to come.